This invention relates to novel chemical compounds which have antibacterial activity, and which are useful in the chemotherapy of bacterial infections in mammalian subjects. More particularly, the novel antibacterial agents of this invention are derivatives of the well-known macrolide antibiotic, erythromycin A, the compound of the following chemical structure: ##STR1## Even more particularly, the novel antibacterial agents of this invention are derivatives or erythromycin A, in which the 14-membered lactone ring has been expanded to a 15-membered ring by insertion of a nitrogen atom between ring-members 9 and 10, and the 4"-alpha-hydroxy group has been replaced by a substituent bonded to the 4"-position through a nitrogen atom (e.g. a primary amino group).
Thus the antibacterial agents of this invention can be regarded as derivatives of the compound of the formula II, viz.: ##STR2## and for the purposes of this specification, the structure II is named chemically as 9a-aza-9a-homoerythromycin A, i.e. the locant 9a is used to identify the additional ring member in the lactone ring.
9a-Aza-9a-homoerythromycin A compounds have been disclosed in published British patent application No. 2,094,293 and U.S. Pat. No. 4,328,334, where they are named as 11-aza-10-deoxo-10-dihydroerythromycin A compounds. 4"-Deoxy-4"-amino-erythromycin A antibacterial agents are known from U.S. Pat. No. 4,150,220.